In a medium bowl, beat cream cheese, egg yolk, and 1/4 cup sugar until smooth. Roll out each bread slice with a rolling pin. Spread cheese mixture over bread, distributing evenly. Roll up each slice and place seam-side down on a baking sheet. In a shallow dish, combine remaining 3/4 cup sugar and the cinnamon. Brush butter over rollups then roll them in the cinnamon-sugar mixture, until completely coated. Place back on the baking sheet after coating. Cover and freeze for at least 2 hours. Just before serving, preheat oven to 400 degrees F. Bake rollups 10 to 12 minutes, or until golden.